Uiimage Created from Mtkview Results in Color/Opacity Differences

UIImage created from MTKView results in color/opacity differences

Your CGColorSpace is .sRGB but your renderPipelineDescriptor's pixelFormat is .bgra8Unorm. Try changing that line to:

renderPipelineDescriptor.colorAttachments[0].pixelFormat = MTLPixelFormat.bgra8Unorm_srgb

how to display MTKView with rgba16Float MTLPixelFormat

So, it looks like you are very close to the complete solution. But what you have is not quite correct. Here is a Metal function that will convert from sRGB to a linear value which you can then write in your Metal shader (I still suggest that you write to a sRGB texture but you can also write to a 16 bit texture). Note that sRGB is not a simple 2.2 gamma curve.

// Convert a non-linear log value to a linear value.
// Note that normV must be normalized in the range [0.0 1.0].

static inline
float sRGB_nonLinearNormToLinear(float normV)
{
  if (normV <= 0.04045f) {
    normV *= (1.0f / 12.92f);
  } else {
    const float a = 0.055f;
    const float gamma = 2.4f;
    //const float gamma = 1.0f / (1.0f / 2.4f);
    normV = (normV + a) * (1.0f / (1.0f + a));
    normV = pow(normV, gamma);
  }

  return normV;
}

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